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I have a newly acquired headphone amp. I hadn't thought about it and what tubes I might slip into it but the plates are run at 450 volts. The cathode appears to be about 20 volts above ground. So any tubes that are not rated for 450 volts, as the early 6SN7 was 300 and the 6F8G, would not be a good choice. The heater is just under 6 volts.And what are the specs for the Tung-sol round plate since it is from the 40's? 300 or 450 max plate volts?
Any ideas? Thanks.
iBasso DX100,DX50 DX90. Chord Hugo. HiFiman 901 balanced. RSA Intruder, The Lightning. Fostex TH900 balanced, Hifiman HE-6, 560, 500, JH13 Pro balanced. Lyr2, Audeze. All phones balanced mostly with Whiplash cables. Photo gallery: www.pbase.com/jamato8
Edits: 07/13/15Follow Ups:
Whew, 450V is pretty dang high! GTA/GTB tubes will absolutely be necessary.
Does the amp come stock with the 6SN7?
a David Berning design. He stated that with this headphone amp that was just recently reintroduced, he has never had problems with any of the 6SN7 tube types, including GT, which are rated at 300 volts max.I am not sure why he chose to run them so high but also states that the tube life is 10,000 hours in this headphone amp. I don't see how as I assume they have a normal bias for the voltage and while the heater is run close to 6 volts, they are still working but even at 450 and running some pre GTA no problems so far, which I don't totally understand.
It comes with a 12AT7 to a 6SN7 for each channel.
iBasso DX100,DX50 DX90. Chord Hugo. HiFiman 901 balanced. RSA Intruder, The Lightning. Fostex TH900 balanced, Hifiman HE-6, 560, 500, JH13 Pro balanced. Lyr2, Audeze. All phones balanced mostly with Whiplash cables. Photo gallery: www.pbase.com/jamato8
Edits: 07/16/15
10,000 hours would be very low life for an old stock 6SN7.
I've had some 6SN7's go for 30,000 hours without the needle moving on my emissions tester.
I have used 6SN7's and have some of the good ones but I don't have that much experience with life expectancy. So 30,000 hours. . . not a bad lifespan.
Any experience with the 12AT7 types?
iBasso DX100,DX50 DX90. Chord Hugo. HiFiman 901 balanced. RSA Intruder, The Lightning. Fostex TH900 balanced, Hifiman HE-6, 560, 500, JH13 Pro balanced. Lyr2, Audeze. All phones balanced mostly with Whiplash cables. Photo gallery: www.pbase.com/jamato8
Not sure about the specific question on TSRP, but I suspect just about every variant up to the GTA will not cut the mustard for you. So, roughly anything before @ 1950 or so wont like the circuit.
5692 - 275 Volts maximum & maximum 1.75 Watts per section
6SN7GT/WGT -- 300 Volts maximum & maximum 3.5 Watts per section
6SN7GTA/GTB - 450 Volts maximum & maximum 5.0 Watts per section
The Tung Sol round plate is a GT. By definition or convention you have stated the 300V max for a 6SN7GT which I would think applies to the Tung Sol.
Seeing that these rules are frequently broken, who after all runs their 5692s at 275V? I am fairly certain that many circuits run the 6SN7 above the specification, not just Berning. The trade off, I thought was tube life span. I don't know how drastically shortened it actually ends up being.
Steve
10,000 hours.
iBasso DX100,DX50 DX90. Chord Hugo. HiFiman 901 balanced. RSA Intruder, The Lightning. Fostex TH900 balanced, Hifiman HE-6, 560, 500, JH13 Pro balanced. Lyr2, Audeze. All phones balanced mostly with Whiplash cables. Photo gallery: www.pbase.com/jamato8
One thought FWIW ... with an noval to octal adapter, you could take your pick of 6CG7/6FQ7's to use in it too.
is a nice tube. I have a number in NOS.
iBasso DX100,DX50 DX90. Chord Hugo. HiFiman 901 balanced. RSA Intruder, The Lightning. Fostex TH900 balanced, Hifiman HE-6, 560, 500, JH13 Pro balanced. Lyr2, Audeze. All phones balanced mostly with Whiplash cables. Photo gallery: www.pbase.com/jamato8
If you don't already have them, you can pick up the adapters off ebay for @ $40.
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